To the prior art are known a number of different processes for rendering polymers incombustible. Such processes in general are based on the use of metal compounds, especially antimony compounds, in combination with thermally unstable halogenated compounds such as, for instance, chlorinated paraffin waxes.
The metal compound + halogenated compound combination yield satisfactory results as far as the self-extinguishing properties they confer to the polymers are concerned, but they show serious drawbacks, such as: corrosion phenomena in the pieces of equipment in which these materials are processed, and heavy emission of toxic smokes and gases in the case of fire. Moreover, acceptable levels of self-extinguishing properties are achieved only when high concentrations of such combinations are used.